Wouldn’t every guy like their girlfriend to wear a really sexy dress to a party ?

dairy

yes sure – all except the paranoid, controlling, dickless thugs who tend to treat women as their property…. if wearing a sexy dress means getting a black eye at the end of the night for having the temerity to speak to another man, I think most girls would pass on that…
sorry to put a downer on the post, but it happens, unfortunately….
for reference, I would point to the recordings made of the so-called comedian Justin Lee-Collins by his long-suffering – and now thankfully ex – girlfriend.